.88.

ENVIRONKENTAL ISOTOPE- AND EYDROCEEMICAL INVESTIGATION OP BAÜRÜ- AND BOTDCATU GROÜNDWATERS, PARANA BASIN,

(report covering 1989 and 1990)

Kisunelmann, A. Universidade de Sao Paulo, Instituto de Geociencias Centro de Pesquisas de Aquas Subterrâneas

June, 19-91, Sao Pauic .89.

Content of this report

1. Introduction

2. Geological and hydrogeological situation of the Parana- Basin 2.1. The Aquifer 2.2. The Serra Geral Basalt 2.3. The Bctucatu Aquifer

3. Isotope methods used for groundwater-investigation 3.1. 2H- and 180-contents in groundwaters 3.2. i4c- and 13C-contents in groundwaters 3.3. 3He/4He-contents in groundwaters 3.4. 4He-excess data for groundwater-investigation

4. Sampling and analytical methods 4.1. Geochenical and isotope data in the core-samples from the well Presidente Prudente 2 4.2. 2H- and 18O-data of Bauru and groundwaters 4.3. 3H-contents in Bauru- and Botucatu groundwaters 4.4. *3c- and 14C-contents of Bauru and Botucatu groundwaters 4.5. 3He/4He- and He-excess data in deep groundwaters from Botucatu

5. Hydrochenical analyses of Bauru- and Botucatu groundwaters

6. Summary and Advances

7. Future activities

8. 1990-1991 Timeschedule of the Bauru-/Botucatu-Project

9. Cooperating Institutions

10. Tables and figures .90. 1. Introduction

A combined hydrogeochemical and environmental isotope investigation is being carried out in the Bauru- and Botucatu groondwaters. Based on former isotope data, the 2H/18O-, 3H-, 13C-, l*c- and 3He/*He-contents of representative groundwaters out from the Bauru- and Botucatu-aquifer are now investigated to reveal a possible interaction of the groundvater systems and to correlate 14C-groundwater residence tines with groundvater "ages'* derived from other isotope methods.

The area of investigation includes the southwestern part of the State of Sao Paulo and the northern Parana and follows a profile between the border of the Parana Basin to its central part. In the east it covers the city of Analandia and in the west it reaches the city of Presidente Epitacio, including the Londrina region.

Continuing former isotope investigations and in the context of a more detailed isotope investigation, groundwaters were selected in view of different drilling and casing depths to represent Bauru- and Botucatu groundwaters.

In 1989 and 1990, two groundwater sampling campains followed a trajectory from Sao Paulo to the city of Epitacio. Sampling drilling cuts from the new drilled well in Pres. Prudente first time enabled to check for 513C-contents and geochemical composition of this aquifer. Beside the aspect, that i13C-rock data are essential for evaluating carbon isotope hydrochemistry of the inorganic carbon dissolved in groundwater, geochemical data are of interest when interpreting hydrochemical contents of the groundwaters.

Results of hydrogeochemical- and isotope analyses obtained in the 1989 and 1990 campains are given in chapter 10 and a first interpretation of these new data is presented in this report.

2. Geological and hydroqeolooical situation of the Parana- Basin

The main aquifers in the brazilian part of the Parana Basin are the Bauru-, the Serra Geral- and the Botucatu-Piramboia aquifer systems. .91. 2.1 The Br.uru Aquifer

The Bauru aquifer system covers 104 000 km2 in the State of Sao Paulo. It is an unconfined aquifer which is formed from cretaceous sandstones. The average thickness of this aquifer is around 100m but increases towards the central part of the area of investigation.

The Bauru aquifer can be subdivided into four formations: Marilia, Adamantina, Santo Anastácio and Caiua. Because the Caiua is the most effective aquifer, its exploitation through wells with depth between 40m and 200m is intensive. In parallel to this, and due to industrial resp. agricultural activities on its surface, the aquifer is also vulnerable to pollutant input. In consequence to the use of fertilizers in agriculture, N03- contents up to 50 mg/1 are found in Bauru-groundwaters. Beside fertilization, also different industrial activities represent a source for Cr-, Ba-, Hg- and Cd-contamination of Bauru- groundwaters .

2.2 The Serra Geral Basalt

The Serra Geral Basalt is a fractured aquifer system with very inhoinogenous hydraulic characteristics. In the area of investigation only few wells are exploiting this aquifer, as its groundwater yield is not very high. In the first sampling campain two samples of drilling cuts could be obtained and a geochemical analysis (performed at University of Góttingen, FRG) revealed the Serra Geral Basalt being a U- and Th-low, SiO2-dominated and carbonate-low basalt with Fe03- and Al203-contents of 5 and 10 % (weight-%) (comp. tab.2).

2.3 The Botucatu Aquifer

The most important aquifer system of the Parana Basin is the Botucatu- (Piramboia) sandstone. It covers around 800 000 km2 on Brazilian territory and, from the North to the South, belongs to the states do sul, , Sao Paulo, Parana, Santa Catarina and Rio Grande do Sul. .92. The Botucatu aquifer system is constituted by the two sedimentary formations Piraaboia and Botucatu. The Piranboia formation consists of fluvial sandstones. In contrast to the Piraaboia, the Botucatu formation consists of sandstones of eolic origin. The Piramboia and the Botucatu formations are intercalated between the Permian layers of the Passadois Group and the basalt flows of the Serra Geral Formation.

The Botucatu-aquifer is unconfined at the borders of the basin. The unconfined part is only some 10% of its area. The Botucatu aquifer is confined from the basalt flows of the Serra Geral Formation. The thickness of the covering basalt may reach about 2000 a in the center of the Parana-Basin. Hydrogeological studies revealed groundwater recharge rates up to 160 x 10 mvyear f°r Botucatu-groundwaters. The recharge of the aquifer is mainly due to infiltration of rain water in the outcrop areas. Froa the border of the basin towards its central part, groundwater flow direction follows the direction of the diving of the geological units. The Botucatu aquifer is exploited through wells with depths between 150 a and some 3000 m and exploitation pumping rates range from 100 a3/h to 1000 m3/h. In consequence to the flow rates and drilling depths, Botucatu groundwaters in the central part of the Parana Basin are geothermal and represent an important geothermal potential.

In view of the fact that the Bauru- and Botucatu aquifers, from its hydrogeochemical and bacteriological status, are suited for the population's, the industry's and the agriculture's water- supply, a combined hydrogeochemical and environmental isotope investigation is carried out to evaluate possible interaction of the groundwater systems on the basis of environmental isotope methods.

3. Isotope methods used for oroundvater investigation

In this project the application of different isotope methods will be performed to cover the groundwater-ages and to check for deep reaching groundwater-mixing systems. As could be seen even from 14C-data in geothermal groundwater in Pres. Prudente, recent water-input into a deep and geothermal groundwater mixing system could be found and apparently is due to deep reaching fractures in the Serra Geral Basalt and to overexploitation of this well. .93. As initial contents of 14C can vary within a wide range in the aquifers investigated, a separate attempt to evaluate C-isotope evolution on the basis of 13C-data is Bade: beside Measuring 13C-contents in the dissolved inorganic carbon (DIC) of the groundwater, a «ore detailed approach to c-isotope evolution Bust include the 13C-contents in the aquifer materials. Consequently we started to measure 13C-contents in drilling cuts from different depths of Pres. Prudente 2.

As *4C-dating of geotherval groundwaters fails even when correcting with 13C-contents in DIC and host-rock, enforced C-solution and enforced C-isotope exchange between the dissolved inorganic carbon and the carbon in the host-rock takes place and 14C-data consequently only can serve as rough indicators for recent water input. To date these groundwaters, sanples were taken for 3He/4He- and *He-excess-Beasureaents. It is also foreseen in this context to use noble gas aethods to determine recharge-paleotemperatures of the very old groundwaters.

In the following chapters a short desription of the different isotope methods will be given.

2H- and 180-contents in qroundwaters

The measurement of 2H- and *°0-contents in groundwater reveals its meteoric/non-meteoric origin and, in cases of changing recnarge climate (paleotemperatures), 2H- and 18O-data can give hints to very old groundwaters (paleo-ef feet). When applying the noble gas method to reveal recharge temperatures, these ll2H-/180-paleogroundwatersM would be of special interest.

3.2. 14c- and 13C-contents in aroundwater

The 14C-method to determine mean residence times of groundwater covers the dating range between some 2000 and 30 000 years. Because the 14C-content is determined in the inorganic carbon dissolved in groundwater, the initial 14C-content of the system groundwater/aquifer nust be evaluated using the "Chemical Mixing-1* and/or the "C-Isotope Exchange Model". Both models simulate the geochemical evolution of the 14C-content following the groundwater pathway from the infiltration- or recharge area to the sampling site. .94. The models correct for the C-isotope interaction -and depletion of the 14C-signal- between the DIC in the groundwater and the C-component of the rock matrix. The rock carbonate -as one component of C-isotope evolution of DIC in groundvater- is free from 14C but shows typical 13C-contents. 13 As the C-content in atmosperic C02 is near some -24 6-0/00 13C vs. an international standard (PDB), the 13C-content of DIC approaches the 13C-content of the rock. Depending on the formation of the C-component of the rock, the 13C-content can vary in the range +0.5 4-0/00 13C for e.g. limestones and -6 5-0/00 13C in those aquifers, where the C-content in rock is due to secondary C-deposition. It is apparent, that -if both C-components are known with respect to their 13C-content- the 13C-content in DIC offers a scale to evaluate the C-isotopic evolution of the groundwater system considered.

3.3. 3He/4He-contents in qroundwater

The 3He/4He-isotope ratio is 1.4 x 10~6 in the atmosphere of the southern and the northern hemisphere. Beside the solution of atmospheric He, which copies this 3He/4He-ratio into surface waters, 3He is also produced through the decay of 3H in the groundwater. The 3He/4He-ratio therefore is correlated to the total amount of 3H which decayed in the groundwater.

Due to the decay of radioisotopes from natural decay series (U- and Th-series), 3He and 4He are also produced in the earth's crust. This He-source typically shows 3He/4He-ratios in the range between 1 x 10~8 and 1 x 10~7.

In contrast to these He-sources, the mantle helium component is characterized by a 3He/4He-ratio of more than 1 x 10~5.

It is evident, that 3He/4He-data of groundwaters depend on the He-flux from the He-sources into the groundwater and also reflect the He-isotope production within the aquifer-material. Depending on the local situation, 3He/4He-data in groundwater may be used as indicators for the origin of groundwater once e.g. U- and Th-contents in the aquifer material favorate this He-source. • 95. ^He-excess daÇa for oroundwater investigations

If the 3He/4He-ratio is not influenced fro» a mantle he HUB component, the order of magnitude of very high groundvater "ages" say be given with the ^He-excess method. These data are based on the assumption, that only locally produced helium is contributing to the He-excess. Because of He-components that originate from lower aquifer layers, He-"ages" of groundvater often only give a rough approximation to groundvater ages.

4. Sampling and analytical methods

Since 1989 groundvater samples have been collected for hydrochemical and for isotope analyses. These samples were taken from free-flowing and from pumped wells exploiting the Bauru, the Serra Geral and the Botucatu-Piramboia aquifer systems in both the unconfined and the confined areas. As drilling cuts could be obtained from the well in Presidente Prudente 2, geochemical investigations and the measurement of the U-, Th- and 13C-content could be performed in samples from the Serra Geral Basalt. To detail the 13C-isotope contents, a depth profile of the 13C-contents will be measured covering the Bauru-, the Serra Geral- and the Botucatu-layersJ This depth- profile is of special interest in view of the 13C-isotope evolution of the groundvaters considered and details the calculation of the initial 14C-content when dating these groundwaters.

4.1 Geochemical and isotope data in the core-samples from the well Presidente Prudente 2

Rock samples investigated for their 13C-isotope contents and for their geochemical composition originate from the well Pres. Prudente 2. They correspond to the lower layer of the Serra Geral Basalt which covers the Botucatu. When compared to mean geochemical contents of basalt, A12O3-, FeO-, Na2O- and K20-contents of the Serra Geral Basalt fit the •ean values for basalts as e.g. given in literature. Referring to the SiO2- and Fe2O3-contents, the Serra Geral Basalt shows •lightly elevated contents, whereas its K-, CaO- and MgO- contents are comparatively low. Low CaC03- and MgO-contents would cause weak mineralisation and e.g. low Ca- and Mg- contents of groundvaters percolating the Serra Geral Basalts. .96. As turned out from very low U- and Th-contents in the Serra Geral Basalt, this aquifer can not be regarded as a dominating source for 3He/*He- or 222Rn-production.

The 13C-contents measured in these rock samples refer to carbonates fro» non-marine origin. As both 13C-contents give 13 the < CROCK-co«ponent# an experimental value -as a sain parameter for the C-isotopic evolution in the Serra Geral- already could be determined.

4.2. 2H- and 18O-data of Bauru and Botucatu aroundwaters

Isotope data of groundvaters are given in tab. (4). In fig. (l) the 2H- and 180-contents of the groundvaters are plotted together with the mean global meteoric water line (GMtfL) 6 2H - 8 6 18O + 10 (o/oo) . As all 2H- and 180-contents of the groundwaters follow the meteoric precipitation line, all groundwaters -and even the groundwaters from the very deep wells- are of meteoric origin and recharged through precipitation.

For the recharge area of the Bauru aquifer, which is close to the recharge area of both the Serra Geral Basalt and the Botucatu-Piramboia aquifer system, a four-years mean value of -6.0 f-o/oo 180 was measured in precipitation from MARTINEZ. 180-contents measured in groundwaters from the Bauru and Botucatu aquifer vary within '9.8 and -6.3 f-o/oo. Groundwater samples from the unconfined aquifers show mere positive 18o- contents which may be an indication for recent groundwater contribution. In contrast to this, the 180-contents of those groundwaters, which represent the confined Botucatu-Piramboia aquifer are more depleted.

The 2H-contents of Bauru- and Botucatu groundwaters lie within the range -43 and -67 f-o/oo 2H. with the exception of the geothermal groundwaters in Pres. Prudente and Pres. Epitacio, and with the exception of the groundwaters from Avare well 7 and from Pratania, the groundwater samples representing the confined Botucatu aquifer show more negative 2H-contents (see fig.l). Through direct comparison it can be deduced, that groundwater from wells in Avare show differing 2H- and 180- contents. A possible explanation could be a different admixture of surface-near groundwaters to the deep Botucatu-groundwater sampled in well 7. .97. 2 18 Th* H- and 0-contents in groundvaters fro» Areiopolis PS( from Avare well 5 and 6 indicate a tendency, that groundvaters from confined Botucatu show «ore negative values. The 2H- and 18O-contents fro» thermal groundvaters in Pres. Prudente and Pres. Epitacio do not fit this picture. In the case of the groundwater in Pres. Prudente, 2H-, 180- and 14C-data however support the assumption, that recent groundwater is admixed due to a pimping rate as high as 1000m3/h.

4.3. 3H-contents in Bauru- and Botucatu aroundwaters

Due to the very low content of 3H in rain of the southern hemisphere, the 3H-content -even in recent groundvaters» is in the range of 5 TO. Measurements of the 3H-content in Bauru-/Botucatu groundwaters is therefore only tried in the Avare-system, to reveal a very recent groundwater component. As 3H-contents below 1 TV were measured in these groundwaters, a contribution of very recent water exceeding 30 % can be excluded in the groundwater from well Avare P7.

4.4. 13C- and 14C-contents of Bauru and Botucatu aroundwaters

13C- and 14c-results measured in groundwaters DIC are listed in tab. (2) and cover the range from -5.2 and -18.9 S-o/oo 13C resp. 8 to 100 pmc. Unfortunately the results of samples 26, 27, 41, 43 and 44 are missing but a few facts already can be stated.

As the 13C-content in thermal waters from Pres. Prudente reaches -6 resp. -7 o/oo 613C, a direct comparison with -4 to -6 o/oo Í13C -as measured in rock material of the Serra Geral Basalt- reveals that C-isotopic evolution in DIC approximates -6 resp. -7 o/oo i13C.

It can be deduced from the 14Ocontent in the geothermal groundwater from Pres. Prudente, that surface near groundwaters are admixed to the Botucatu groundwater. This may be due to a high pumping rate and/or to a bad casing. An admixture of surface-near groundwater does not affect the isotopic signature of the 13C-content in DIC, because of the different "signal to background ratios" between 14C and 13C.

10 .98. Apparent from 13c- and l4C-contents in groundwaters fro» Avar* PS and froa Areiopolis P5, no admixture rf surface near groundvater to the Botucatu-groundwater takes place in these wells. Mean residence tiaes of these groundwaters correspondingly are high and will be evaluated using the Isotope Exchange Model to calculate the initial content of l4C.

Groundvater froa de Sao Manoel P2 represents groundwater froa the unconfined Serra Geral Basalt and its intertraps. The 14C-content shows 104.00 +- 5.0 pac and -fitting with expectation- indicates a very recent groundwater.

— and He—excess data In deep enroundwaters fi Botucatu

3He/4He-saaples were taken froa groundwater in Avare P5, in Presidente Prudente and in Pres. Epitacio. 3He/4He-ratios listed in tab.(4) show ratios in the range of 10~7 to 10~*. Despite the low D- and Th-contents aeasured in the saaples froa Serra Geral Basalt, excess He- (given in 10*~* Mai He per graaa of water) can be stated in all groundwaters investigated. Referring to the thermal groundwaters in Pres. Prudente and Pres. Epitacio, a clear indication for an He-excess can be derived from 4000 - 11000*10** Nal He per graaa of water. These results however can be influenced froa outgassing due to very difficult sampling conditions.

5. Hydrochemical analyses of Bauru and Botucatu aroundwaters

The hydrochemical data are listed in tab.(3). Because the Bauru and the Botucatu sandstone layers show low carbonate contents, their groundwaters are only weakly aineralised and e.g. HCO3- contents below 200 ag HCO3/1 were aeasured. Even in the geotheraal groundwaters in Pres. Prudente and Pres. Epitacio HC03-contents do not exceed 510 ag HCO3/I.

When compared to non-geotheraal groundwaters in the Bauru and Botucatu-layers, geothemal groundwaters show elevated HCO3-, Cl-, Ha- and SO4-contents but are depleted in their Ca- contents. As the SO4-content does not correlate with the Ca- or Mg-contents of the groundwaters, S04-contents are not due to Ca/MgS04-solution, it is also evident, that Ca-contents in the theraal groundwaters are lover than in the other groundwater» investigated. CaC03-contents in the deep layers of the Botucatu aquifer consequently are assuaed to be lower than in the aquifer layers above. .99. When comparing the Ca/Mg-ratio of the groundwaters with the CaO- resp. MgO-contents as measured in the deeper layers of the Serra Geral Basalt (see tab.2), geothermai groundwaters fit a Ca/Mg-ratio between 1.5 and 2 whereas other groundwaters show slightly higher Ca-contents but same Ca-/Mg-ratios and may indicate aquifer-layers with Ca/Mg-ratios differing from the basalt. Referring to the Na- and Cl-contents in the geothermai groundwaters, the influence of NaCl-solution out from deeper aquifer layers, resp. the influence of a groundwater with higher Na- and Cl-contents is obvious and perhaps may fit the geochemical analyses which will be done on the Botucatu- drilling cuts.

6. Summary and Advances

During the first phase of the project, three field trips for sampling have been done. First hydrochemical parameters and environmental isotope-contents of groundwaters sampled in both campains are measured and results are listed in tabs. (3) and (4).

As samples of drilling cuts could be obtained from the well Pres. Prudente 2, first uranium-, thorium and 13C-contents of rock material could be determined in the lower layers of the Serra Geral Basalt.

As the U- and Th-determinations in the basalt are of interest in view of applicating the He-isotope-method to date groundwater, the 13C-content in rock material is necessary for evaluating the isotope evolution of 13C and 14C in the dissolved inorganic carbon (DIC) of the groundwaters investigated.

It can be seen from hydrogeochemical data, that all groundwaters -and even the geothermai ones- show only small mineralisation which is due to the low calcium-carbonate contents of the Bauru- and Botucatu-sandstone aquifers. As Na- and Cl-contents of the geothermai groundwaters out from the deep layers of the Botucatu are elevated, the influence of another aquifer resp. the admixture of a groundwater with higher Na- and Cl-contents can be assumed.

12 .100. A first interpretation of isotope contents measured in the Bauru and Botucatu groundwaters reveals, that based on a 13O contents between -4 to -6 o/oo-6*3C. as measured in the rock material, -6 to -7 o/oo-613C in the PIC of the Botucatu- groundwaters are the endpoint of 13C-evolution between the systems Die in groundwater and rock carbonate.

As can be deduced from 14C- (13C-) data, groundwaters 'n Avare P5 and Areiopolis represent Botucatu-groundwaters with high mean residence times. This conclusion is supported from 2H- and 18O-data of these groundwaters, when compared with the 2H- and 180-contents of the recent groundwaters e.g. in Sao Manoel. The groundwater system in Avare will be of special interest, because 2H- and 18O-data support the opinion, that a groundwater mixing system is represented in wells 5, 6 and 7.

The geothermal groundwater in Pres. Prudente represents the groundwaters from the deep layers of the Botucatu. The 14C- content was supposed to be below the detection limit of 2 pmc due to enforced C-isotope solution and -exchange. Contradicting our opinion, the 14C-content in this groundwater was IS pmc. As contamination of the sample is improbable, the only explanation is the high exploitation-rate (up to 1000 m3/h) and/or an insufficient casing of this well, which conceedes a young groundwater component to be admixed to the geothennal, old Botucatu groundwater.

First 3He/4He- and He-excess data are obtained in groundwaters from Avare, Pres. Prudente and Pres. Epitacio. As no significant 3He/4He-differences could be stated in the Botucatu groundwaters, a 3,,e/4He ratio in the range of 3*10"8 is taken to represent deep Botucatu-groundwaters. Due to severe difficulties when sampling for He-excess data, only the order of magnitude of the He-excess in the geothermal groundwaters can be derived from data obtained. Nevertheless, a He-excess in the deep Botucatu layers could be stated and will be the subject of further investigation.

7. Future activities

Future investigations will cover a more detailed study of the groundwater systems in Avare and Areiopolis using 14C- and He- isotope analyses. It is also intended to measure noble gas contents in these groundwaters (cooperation with M. Stute/Lamont University), to investigate recharge- paleotemperatures of these groundwaters and to compare with the noble-gas-data obtained from geothermal Botucatu-groundwaters.

13 .101. To contribute to C-isotope evolution of groundwaters and to seek for a variation of the 13C-content in the different 13 aquifer-layers, a CRocJC-depth-profile will be measured in drilling cuts from the well Pres. Prudente 2. These data will represent different layers of the Bauru-, the Serra Geral- and of the Botucatu/Piramboia Formation.

Concerning the deep Botucatu layers and its geothermal groundwaters, future isotope investigations should include 222Rn-measurements and will include Ra- and 3He/4He-isotope investigations. In view of the low U- and Th-contents it is also intended to sample the deep Botucatu-groundwaters for a few 36Cl/Cl-deteriBinations. In the context of Ra- and Rn-data, which will be used to check for subsurface production of 36Cl, an attempt to date the very old groundwater with the 36C1- isotope method will be undertaken.

8. 1990-1991 Timeschedule of the Bauru-/Botucatu-Proiect

November, 1990 IAEA-experts visit in Sao Paulo, field campain

June/August 1991 field trip for collecting further groundwater samples to determine 3He- and 4He-contents, to measure noble-gas recharge temperatures and to supply further 14C-, 13C-, 2H- and 180- measurements of both groundwater systems

Okt./Nov. 1991 IAEA-experts visit intended for preliminary data treatment and data-interpretation.

14 .102. 9. Cooperating Institutions Hydrochemical investigations were measured in the CEPAS laboratory of USP, Sao Paulo, Brazil.

The He-sampling device used for He-sampling was machined at the laboratory of CEPAS-USP-Sao Paulo, Brazil.

The University of Gõttingen performed the geochemical analyses of the Serra Geral samples given in tab.(2).

The determination of the stable isotopes 180-, 2H- and the 13C- analyses were performed in the laboratory of CENA-USP- Pi racicaba, Brazil.

The measurement of the specific activity of 14C in DIC and the 3He/4He- as well as the 3H-determinations were performed at the environmental isotope laboratory of IfH, GSF-Neuherberg, Germany.

Further samples for 14C-measurements in groundwater will be analysed at the radiocarbon laboratory of CENA-USP - , Brazil.

15 .103. 10. Tables and figures

Tab. 1: Groundwaters sampled are given with reference to their type of aquifer and their aquifer layers.

sample site/veil aquifer-layer type

25 Avaré P-5 Botucatu Piramboia confined

26 Avaré P-6 Botucatu-Piramboia confined

27 Avaré P-7 Botucuta-Pirambóia confined

28 Pres.Prud. PI Botucatu-Pirambóia confined

29 Pres. Epitácio Botucatu-Pirambóia confined 30 Pres.Prud. Pia Bauru unconfined 40 Aparecida de Sao Manoel P-2 Serra Geral-Basalt unconfined 41 Aparecida de Sao Manoel P-1 Serra Geral Basalt unconfined

42 Areiópolis ?-5 Botucatu confined 43 Areiópolis P-1 Serra Geral Basalt unconfined 44 Pratânia Baru and Serra Geral-Basalt unconfined 46 Pres.Prud. P2 Botucatu confined

16 .104. Table 2: Results of geochemical analyses of drilling cuts out from well Presidente Prudente 2. Samples represent Gerra serai Basalt at depths 1576 • and 1604 m. (Geochemical analyses from Univ. of Gõttingen, Germany)

Element Depth Depth

1576 m 1604 a

U (mg/kg) 0.880 1.130

Th (mg/kg) 3.340 4.540 13C-content (i-o/oo) -4.6 -6.7

K (%) 0.900 1.500

sio2 61.400 55.100

A12O3 9.720 13.300

Fe2O3 5.100 4.300 FeO 7.020 7.680 Cao 6.520 7.520 MgO 3.220 4.850

Na2O 2.140 3.240

K20 1.300 1.970

Li2O 0.005 0.003

17 Tab. 3: Results of hydrochemical analyses of Bauru- and Botucatu groundwaters.

Saaple Site and sampling HCO3 Cl N03 so4 Na K Ca Mg Nr. well date (mg/D (mg/D (mg/i) (mg/l) (mg/l) (mg/l) (mg/1) (mg/l)

25 Avaré p-5 21.9.89 164.7 0.4 0.1 0.5 15.0 0 .9 7.3 1.2

26 Avaré P-6 21.9.89 142.6 2.4 0.2 0.9 12.0 0.3 9 .2 1.3 27 Avaré P-7 21.9.89 89.2 1.7 nd 1.3 7.0 0.5 12.3 2.3 28 Pres.Prud. PI 22.9.89 385.5 165.0 nd 109 ,3 230.0 2.1 4.7 1.8 29 Pres.Epitácio 23.9.89 506.3 59.7 nd 80 .0 180.0 1.8 0.5 0.9 30 Pres.Prudente 22.9.89 P-la 65.2 1.5 0.2 2 .5 0.6 0 .3 2.9 1.4 40 Aparecida de Sao Manoel P-2 08.2.90 73.2 1.0 5.0 0 .1 2.0 0 .9 10.7 1.8 41 Aparecida de Sao Manoel P-l 08.02.90 54.2 1.0 4.8 0 .1 2.0 0 .9 10 .9 1.9

42 . Areiópolis P-5 09.02.90 134.2 0.1 0.7 1nd 4.4 2.1 19.0 0.7 43 Areiópolis P-l 10.02.90 85.5 0.8 2.1 Ind 6.6 0 .9 11.3 1.4 44 Pratânia 11.02.90 97.6 1.8 9.0 0 .1 2.9 1.7 14 .7 2.9 46 Pres.Prud. P2 21.07.90 506.2 208.0 nd 88 .0 295.0 3.4 2 .4 0.9

nd - below detection limit Tab. 4: Results of isotope analyses of Botucatu and Bauru groundwaters * indicates samples where the result is outstanding L indicates samples which are lost or were contaminated

:L8O 2 13 14 3 Sample Site and sampling Temp. H C C He/< He ^excess Nr. well date CC) (6-0/00) (í-o/oo) (í-o/oo) (pmc ± 2a) *1C,-6 *10"8 Nml/g

25 Avaré P-5 21.9.89 27.0 -8 .61 -56. 6 -12.7 7.6 t 1-6 <0. 04 46 26 Avaré P-6 21.9.89 26.5 -7.66 -51.2 27 Avaré P-7 21.9.89 27.0 -7 .37 -49.5 28 Pres.Prud. PI 22.9.89 60.0 -6 .52 -4 3.1 -6.34 15.0 ± 1.4 0.02 10500 29 Pres.Epitácio 23.9.89 72.0 -6 .94 -48. 6 .12 5000 0 .030 4700 30 Pres.Prudente 22.9.89 P-la 22.0 * * 0 .05 25 40 Aparecida de Sao Manoel P-2 08.2.90 24.0 -7 .01 -45.8 -18.9 104.0 ± 5.0

41 Aparecida de Sao Manoel P-l 08.02.90 24.0 -6 .92 -44.9 42 Areiópolis P-5 09.02.90 28.5 -9 .87 -57. 1 -11.7 17.2 ± 5.0

43 Areiópolis P-l 10.02.90 21.0 -6 .84 -46. 3

44 Pratânia 11.02.90 22.5 -7 .21 -46.4 * L

46 Pres.Prud. P2 21.07.90 70.0 -6 .26 -43. 8 -7.5 * L .107. Fi«. (1): 2H- and 180-contents of Bauru- and Botucatu groundvaater». The Global Mean Meteoric WateNat r Line Í 2H - •8 * Í 180 + 10 (o/oo) is indicated.

I I I I I I 00 Oi Ü O o o o o o Ó2H

20 (A U a 0.06- Pratanio I . I1 •» Ü 0 MH 0.05- Avare P7 0 III

o 0.04-1 P1 Pres. Pruden Sao Manoel E P1 OJ 0 M U • 0$ D> 0.03- Pres. Pruçíente P1a C4J * o » o I H i 0.02- Epltáoio I Pres. Prudente «o o P2 Areiopolís

0.00 0.05 0.10 0.15 0.20 Ca [mvai/l]